Free core grinding drill

ABSTRACT

A core drill designed to insure a core will be generated sufficiently smaller in diameter than the normal inside diameter of the drill, and therefore a free or loose core, to assure easy removal or drop out of the core from the drill. This is accomplished by providing a drill of any predetermined outer diameter and an inner bore providing a smaller inner diameter having longitudinal walls parallel with but offset relative to the longitudinal walls of the outer diameter, therefore, in operation, the running inside diameter rotates eccentrically to the true running outside diameter on a common axis to generate a core having a smaller diameter than the inside diameter of the core drill.

United States Patent 1 Wing [451 Feb. 27, 1973 FREE CORE GRINDING DRILL[76] Inventor: Frederick Donald Wing, 145 Beacon Lane, Jupiter lnletColony, Jupiter, Fla. 33458 [22] Filed: Dec. 28, 1970 [21] Appl. No.:101,507

[52] US. Cl ..l25/20, 175/398 [51] Int. Cl. ..B28d 1/14 [58] Field ofSearch ..175/398, 399, 400; 125/20; 51/209 [56] References Cited UNITEDSTATES PATENTS 3,169,415 2/1965 Welty ..125/20 X 3,243,924 4/1966 Peters........125/20 2,425,132 8/1947 Stoken ..175/400 X 3,077,936 2/1963Arutunoff.... ..l75/l07 X 3,153,885 10/1964 Keller ..125/20 X 3,033,2985/1962 Johnson ..l24/20 UX 3,494,348 2/1970 Lindblad 125/20 FOREIGNPATENTS OR APPLICATIONS 119,771 4/1901 Germany ..175/400 PrimaryExaminer-Harold D. Whitehead Attorney-Meyer A. Baskin 5 7 ABSTRACT Acore drill designed to insure a core will be generated sufficientlysmaller in diameter than the normal inside diameter of the drill, andtherefore a free or loose core, to assure easy removal or drop out ofthe core from the drill. This is accomplished by providing a drill ofany predetermined outer diameter and an inner bore providing a smallerinner diameter having longitudinal walls parallel with but offsetrelative to the longitudinal walls of the outer diameter, therefore, inoperation, the running inside diameter rotates eccentrically to the truerunning outside diameter on a common axis to generate a core having asmaller diameter than the inside diameter of the core drill.

4 Claims, 6 Drawing Figures SHEET 1 0F 2 IN VENTOR. FREDERICK DONALDLU/lbK-I BY W fiTTOR/UEX PATENTED FEBZ 7 I973 J ML FREE CORE GRINDINGDRILL This invention relates to a type of drill commonly referred to asa trepanning tool or core drill which will hereinafter be referred to asa core drill.

In the present art, one of the major technical problems has been in theremoval of the core after the core drilling operation was completed. Thecore being of the same outside diameter as the inside diameter of thecore drill, together with sludge from the ground material itself,combine to hold the core in the core drill and make its removaldifficult and time consum- A liquid coolant is usually used with anabrasive core drill by introducing the coolant in to or onto the coredrill and the material being worked. Since the core fills the insidediameter of the core drill, and the outside diameter of the core drillfits the hole being drilled, very little of the coolant reaches theannular surface being abraded on the material, after the core drill haspenetrated a relatively short depth. Excessive friction heat isgenerated as the core drill penetrates further into the work andtherefore, less coolant can reach the surface being abraded. The speedof rotation of the core drill must then be reduced in order to reducethe friction heat being generated resulting in slowing down theoperation and consuming more time.

In the present art also, frequently the core has become more or lesswedged inside of the core drill. This core then exerts pressure on thebottom of the material being drilled, and in combination with thefriction heat being generated, can and does cause the cored area tobreak out irregularly at the other side or end of the material beingdrilled, before the core drill has completed the hole. This frequentlyhappens on more fragile or brittle material which is very often also themost expensive materials such as glass, fused quartz, fused silica,silicon, germanium, porcelain, ceramics, and many other materials.

There is a strong need, therefore, for an abrasive type core drill thatwill overcome the foregoing difiiculties and shortcomings.

It is an object of the invention to provide an abrading core drill thatgenerates a smaller core than the inside diameter of the core drillitself,=resulting in a core that will drop out after a core drillingoperation, or be, easily removed by providing such a drill in which theinner diameter is eccentric relative to the outside diameter thereto.

Yet another object of the present invention is to provide a drill havinga cutting edge of the type utilizing a grinding action as provided by adiamond, silicon carbide, or other abrasive material impregnated cuttingedge, said edge having an inner diameter eccentric to its outer diameterin general conformity with the inner and outer diameters of the mainbody portion of the drill. While the eccentric inner diameter may haveother contours it is preferably circular.

Still another object of this invention is to provide a drill of theaforementioned type which may be provided with various conventionaltypes of liquid cooling means preferably of the type which feeds coolantthrough the shank of the drill under pressure downwardly through thebody portions thereof to the grinding edge as it rotates in contact withthe work.

Yet another object of this invention is to provide a drill which willgrind a wide variety of materials such as hard metals, vitreous andceramic materials, glass, tile, porcelain, cement, pavements, marble,granite and other rock type materials, for example.

Another object of this invention is to provide a drill which may bemounted in a portable hand drill and not be limited to mounting in amachine tool such as a milling machine, boring mill, or drill press.

It is a further object of this invention to allow the coolant freeraccess to the annular surface being abraded, therefore reducing thefriction heat being generated. The freer coolant flow, in addition tocarrying away the friction heat being generated, also aids in carryingaway the residue or sludge of the material being core drilled.

Still another object of the invention is to reduce the pressure the snugfitting core would have on the opposite end of the material beingworked, and many times causing an irregular break out, before the coredrilling operation is actually complete.

With the above objectives in view, as will be presently apparent, theinvention consists in general of certain novel construction and geometryhereinafter fully described, illustrated in the accompanying drawingsand particularly claimed.

Whereas the drawings show a type of abrad ing core drill with a bondeddiamond or abrasive annular end or edge. This invention includes coredrills that may be.

solid abrasives all the way up the main body of the tool or may be plainmetal or other materials to be used with loose abrasives or abrasiveslurries.

DESCRIPTION OF THE PRIOR ART U.S. Pat. No. 1,187,618 issued to G. O.Gridley shows a drill restricted to for cutting an annular groove. Thisdrill employs an eccentric relationship between the inner and outerdiameters thereof, however, the inner eccentric bore is helical insteadof straight through which would be very difficult to produce and make itimpossible to core drill through any material of any significantthickness. In addition, the cutting edge employs a single cutting pointor tooth instead of providing a grinding surface about its lower annularface. The tool of this patent is clamped or held stationary and the workis rotated. It is therefore not portable to the material and it couldnot be used, for example, to mount in a hand drill and bore a hole in alarge immovable concrete structure or road bed, some distance away.

U.S. Pat. No. 2,444,099 issued to S. W. l-lennessey, Jr., illustrates ahole cutting saw with up to 20 teeth which are difficult to sharpenwithout affecting the diameter of the drilled holes. This patent isdependent on wide area cutting saw teeth to eliminate troubles caused bysmaller saw teeth, making it necessary to remove more material toachieve the desired result. The lower end of the spindle forms a pilotwhich is received within a central opening which has been previouslydrilled or punched into the material.

U.S. Pat. No. 2,947,206 issued to H. J. Flanagan shows a trepanningdrill which is not new in itself and provides no eccentric insidediameter to effect a free core and U.S. Pat. No. 3,227,103 issued to L.Zimmerman is also a toothed cutting tool, providing a Pair of cuttingelements one tooth cuts the outside diameter and the other cuts theinside diameter.

DESCRIPTION OF THE DRAWING FIG. 1, is an isometric view of the coredrill of the present invention;

FIG. 2, illustrates a side elevational view of the core drill of thepresent invention performing a drilling operation, parts being brokenaway to better illustrate the invention;

FIG. 3, is a cross sectional view taken on line 3-3 of FIG. 2, lookingin the direction of the arrows;

FIG. 4, is a view like FIG. 3 showing a modification;

FIG. 5, is a view like FIG. 3 showing still another modification, and

FIG. 6, schematically illustrates one application of providing a coolantto the core drill during the drilling operation.

In the drawings in which like reference numerals designate like orsimilar parts throughout the several views of the drawings, the numeralgenerally indicates the core drill of the present invention whichincludes a main body portion indicated generally at 12, and a shankportion 14 provided for engagement in the chuck a conventional type offixed machine tool or portable hand drill.

The core drill of the present invention is shaped generally like a pipeand is provided with a diamond or silicon carbide or other abrasivematerial impregnated cutting edges. At the present time with the toolsin general use, the core, or plug generated by drilling through the workmaterial too often becomes wedged inside the tool thus creating aremoval problem and in some cases, the pressure caused by this wedgingcan cause a fracture breakthrough of the material being drilled whichresults in rejection of or damage to the part being drilled.

To obviate this objectional feature of many of the tools of this typenow in use, the main body or working portion 12 of the tool of thepresent invention provides an outer diameter 16 and an inner bore orcavity 18 which provides an inner diameter 20 which is eccentricrelative to the outer diameter 16.

As best illustrated in FIG. 2, the broken line xx illustrates the commonrotating axis of the shank and outer working diameter 16 of the tool 10.And the broken line y-y shows the axis of the inner bore 18 which isparallel to and offset relative to the axis of rotation x-.r whereby theinner diameter 20 rotates eccentrically relative to outer diameter 16 onthe common axis x-x.

A diamond, silicon carbide or other abrasive impregnated grinding endsection 24 is provided on the tool which is bonded or plated to thelower end of the main body portion 12. The entire section 24 will beused as said section wears down. The cutting end section 24 providesouter and inner diameters 26 and 28 in an eccentric relationshipconforming to the eccentric relationship of the outer and inner diameter16 and 20 of the main body portion 12 of the tool 10. The outer diameter26 may be slightly larger than the outer diameter 16 of the main bodyportion 12 and the inner diameter 28 may be slightly less than the innerdiameter of the inner diameter 20 of themain body portion to provide arelief 30 between the outer diameter 16 of the main body portion 12 andthe outer diameter 32 of the hole being drilled in the work W. In likemanner a relief 34 is provided between the inner diameter 20 of the mainbody portion 12 and the outer diameter 36 of the core 38 being generatedby the drilling operation in the work W.

As best illustrated in FIG. 3, a free core 38 is generated by the tool10 of the present invention due to the eccentric relationship betweenthe outer and inner diameter 26 and 28 of the grinding end 24. Thethickest point 22 in the wall of the grinding end section 24 rotates inthe same are as the resulting core.

FIG. 6, schematically illustrates one form of provid ing a coolant tothe cutting end of the tool during the drilling operation. A bore 40 isprovided axially of the shank portion 14 and into the main body portion12 of the drill, communicating with the inner diameter 20 and thegrinding end 24, and one or more diametrically disposed bores 42 areprovided in communication with said bore 40. A housing 44 is sealinglycircumposed about the outer circumference 14 of the shank portion 14 ofthe drill and provides an inner annular chamber 46 in directcommunication between the axial bore 40, by means of the diametric bores42, and a coolant feed line 48 from a feed source (not shown). Thecoolant is preferably fed to the cutting edge 24 under pressure. Otherforms or methods of providing a coolant to the cutting or grinding edgethrough the axial bore may be employed. In some instances the coredrill. may also be used without coolant.

The modifications shown in FIGS. 4 and 5 shows an inward protrusionwhich would have the same effects and results as the preferredcontinuous circular eccentric bore as shown in FIG. 3. In themodification shown in FIG. 4 the inward protrusion 39 on the insidediameter D' is shown as of the arc of the inside circle. While thisproportion is shown for clarity, the protrusion could be of any arclength from a bare minimum up to of arc.

In the modification shown in FIG. 5 there is shown a flat section 41along the otherwise circular inside diameter.

With reference to FIGS. 3,4, and 5 it is clearly apparent that the threeforms illustrated are provided with respective grinding ends 24, 24' and24" providing corresponding thick points 22, 22 and 22" wherebycorresponding cores 38, 38 and 38" are generated. The respective formsillustrated in FIGS. 3, 4, and 5 provide similar diameters D, D and D"between said thick points 22, 22' and 22" and their respective opposedside wall portions as well as similar respective locations of the axesof rotation x-x, xx' and x"--x", and bore axes y-y, y'-y' and y"y".Therefore, each of said forms provides a bore having at least oneportion which rotates eccentrically about their respective axes ofrotation x-x, x'x and x"-x relative to their respective diametricallyopposed side wall portions.

While .a preferred form of the invention has been illustrated anddescribed, it will be obvious to those skilled in the art that variousmodifications and substitutions can be made without departing from thescope of the invention as defined in the appended claims.

What is claimed is:

1. A Core Drill Comprising:

A. A shank portion adapted for rotative engagement in the chuck of adrilling or rotative apparatus;

B. A cylindrical working body portion having,

1. an outer diameter the axis of rotation of which is common to the axisof rotation of said shank portion,

2. an inner bore extending a predetermined distance upwardly into saidmain body portion, said inner bore having,

a. the major portion of its cylindrical wall extending substantiallycoaxially with the axis of rotation of said main body portion, and

. minor portion of its cylindrical wall having a diameter slightly lessthan the diameter of said major portion of said wall and extendingsubstantially on an axis displaced from and parallel to the axis ofrotation of the main body portion on which the major portion of saidcylindrical wall rotates whereby the minor portion of the cylindricalwall of said inner bore rotates eccentrically to the major portion ofsaid cylindrical wall,

3. an operative grinding end;

C. A grinding means at said operative grinding end extending 360thereabouts whereby the grinding operation is performed substantiallyand simultaneously around the entire 360 of said grinding end.

2. A core drill for optical quality material as defined in claim 1including a central bore extending axially through the shank and intothe said working, body portion whereby a liquid coolant may be suppliedto said grinding end during the drilling operation.

3. A core drill as defined in claim 2, in which the outer diameter ofsaid grinding means is slightly larger than the outer diameter of saidbody portion and the inner diameter of said grinding means is slightlysmaller than the inner diameter of said eccentric bore.

4. A core drill is defined in claim 1 in which said eccentric minorportion comprises an inward protrusion on said inside diameter of saidbore.

1. A Core Drill Comprising: A. A shank portion adapted for rotativeengagement in the chuck of a drilling or rotative apparatus; B. Acylindrical working body portion having,
 1. an outer diameter the axisof rotation of which is common to the axis of rotation of said shankportion,
 2. an inner bore extending a predetermined distance upwardlyinto said main body portion, said inner bore having, a. the majorportion of its cylindrical wall extending substantially coaxially withthe axis of rotation of said main body portion, and b. minor portion ofits cylindrical wall having a diameter slightly less than the diameterof said major portion of said wall and extending substantially on anaxis displaced from and parallel to the axis of rotation of the mainbody portion on which the major portion of said cylindrical wall rotateswhereby the minor portion of the cylindrical wall of said inner borerotates eccentrically to the major portion of said cylindrical wall, 3.an operative grinding end; C. A grinding means at said operativegrinding end extending 360* thereabouts whereby the grinding operationis performed substantially and simultaneously around the entire 360* ofsaid grinding end.
 2. an inner bore extending a predetermined distanceupwardly into said main body portion, said inner bore having, a. themajor portion of its cylindrical wall extending substantially coaxiallywith the axis of rotation of said main body portion, and b. minorportion of its cylindrical wall having a diameter slightly less than thediameter of said major portion of said wall and extending substantiallyon an axis displaced from and parallel to the axis of rotation of themain body portion on which the major portion of said cylindrical wallrotates whereby the minor portion of the cylindrical wall of said innerbore rotates eccentrically to the major portion of said cylindricalwall,
 2. A core drill for optical quality material as defined in claim 1including a central bore extending axially through the shank and intothe said working, body portion whereby a liQuid coolant may be suppliedto said grinding end during the drilling operation.
 3. A core drill asdefined in claim 2, in which the outer diameter of said grinding meansis slightly larger than the outer diameter of said body portion and theinner diameter of said grinding means is slightly smaller than the innerdiameter of said eccentric bore.
 3. an operative grinding end; C. Agrinding means at said operative grinding end extending 360* thereaboutswhereby the grinding operation is performed substantially andsimultaneously around the entire 360* of said grinding end.
 4. A coredrill is defined in claim 1 in which said eccentric minor portioncomprises an inward protrusion on said inside diameter of said bore.